{"id":{"repo_id":"vt","oai_identifier":"oai:vtechworks.lib.vt.edu:10919/37216"},"canonical_url":"https://search.dev.ndltd.org/etd/vt/oai:vtechworks.lib.vt.edu:10919/37216","repository":{"repo_id":"vt","name":"Virginia Tech","base_url":"https://vtechworks.lib.vt.edu/oai/request"},"display":{"title":"Effect of fiber/Matrix Interphase on the Long Term Behavior of Cross-Ply Laminates","abstract":"A systematic study was conducted to examine the influence of fiber surface treatment and sizing on the formation of fiber-matrix interphase and its effects n the mechanical properties of composite laminates. Three material systems having the same Apollo graphite fibers and HC 9106-3 toughened epoxy matrix, but with different fiber surface treatments and sizings were used in this study. The fibers used in the 810A and 820 A systems received 100% and 200% industry standard surface treatments respectively and were sized with Bisphenol-A unreacted epoxy material. The 810 O system was manufactured with 100% surface treated fibers that were sized with pvp (polyvinylpyrrolidone), a thermoplastic material. The presence of different interphase in these materials was confirmed using a permanganic etching technique. Results indicate that the interphase is discontinuous and made of linear chain polymeric material in the 810 A system. The interphase in the 810 O system has a gradient morphology while the 820 A system does not possess a well defined interphase. Mechanical test results indicate that the 810 O system significantly greater longitudinal tensile strength and failure strain compared to the 810 A system. The 810 A and 820 A systems have similar longitudinal tensile properties. Transverse tensile test results indicate that the 820 A system has the highest strength while the 810 O system has the lowest strength. The (0,90₃), cross-ply laminates from the three material systems exhibit different damage mechanisms and failure modes under monotonic tensile loading. Fatigue test results indicate that the 810 O laminates have longer fatigue lives at higher load levels and shorter fatigue lives at lower load levels compared to the 810 A laminates. The 820 A laminates have longer life compared to the other two materials systems, at all three load levels. The 810 O material exhibits greater damage and stiffness reduction than the other two materials. The 810 A and 820 A systems exhibit a brittle stress concentration controlled failure, while the pvp sized 810 O system exhibits a global strain conuolled failure. A micromechanics model was developed to investigate the role of the interphase on the tensile strength of unidirectional laminates. A new parameter called the ‘efficiency of the interface’, is introduced in the model. A simple scheme that uses the experimentally determined tensile modulus of unidirectional laminates in a concentric cylinders model, is described to estimate the interfacial efficiency. The tensile fatigue performance of cross-ply laminates is predicted using this micromechanics model in a cumulative damage scheme. The predicted fatigue lives and failure modes agree well with experimental results.","abstract_html":"A systematic study was conducted to examine the influence of fiber surface treatment and sizing on the formation of fiber-matrix interphase and its effects n the mechanical properties of composite laminates. Three material systems having the same Apollo graphite fibers and HC 9106-3 toughened epoxy matrix, but with different fiber surface treatments and sizings were used in this study. The fibers used in the 810A and 820 A systems received 100% and 200% industry standard surface treatments respectively and were sized with Bisphenol-A unreacted epoxy material. The 810 O system was manufactured with 100% surface treated fibers that were sized with pvp (polyvinylpyrrolidone), a thermoplastic material. The presence of different interphase in these materials was confirmed using a permanganic etching technique. Results indicate that the interphase is discontinuous and made of linear chain polymeric material in the 810 A system. The interphase in the 810 O system has a gradient morphology while the 820 A system does not possess a well defined interphase. Mechanical test results indicate that the 810 O system significantly greater longitudinal tensile strength and failure strain compared to the 810 A system. The 810 A and 820 A systems have similar longitudinal tensile properties. Transverse tensile test results indicate that the 820 A system has the highest strength while the 810 O system has the lowest strength. The (0,90₃), cross-ply laminates from the three material systems exhibit different damage mechanisms and failure modes under monotonic tensile loading. Fatigue test results indicate that the 810 O laminates have longer fatigue lives at higher load levels and shorter fatigue lives at lower load levels compared to the 810 A laminates. The 820 A laminates have longer life compared to the other two materials systems, at all three load levels. The 810 O material exhibits greater damage and stiffness reduction than the other two materials. The 810 A and 820 A systems exhibit a brittle stress concentration controlled failure, while the pvp sized 810 O system exhibits a global strain conuolled failure. A micromechanics model was developed to investigate the role of the interphase on the tensile strength of unidirectional laminates. A new parameter called the ‘efficiency of the interface’, is introduced in the model. A simple scheme that uses the experimentally determined tensile modulus of unidirectional laminates in a concentric cylinders model, is described to estimate the interfacial efficiency. The tensile fatigue performance of cross-ply laminates is predicted using this micromechanics model in a cumulative damage scheme. The predicted fatigue lives and failure modes agree well with experimental results.","abstract_has_math":false,"creators":["Subramanian, Suresh"],"institution":"Virginia Tech","degree_name":"Ph. D.","degree_level":"doctoral","degree_discipline":"Engineering Science and Mechanics","degree_department":"Engineering Science and Mechanics","school":null,"contributors":[],"advisors":[],"committee_chairs":["Stinchcomb, Wayne W."],"committee_members":["Kander, Ronald C.","Kriz, Ronald D.","Loos, Alfred C.","Reifsnider, Kenneth L."],"year":1994,"date_issued":"1994-01-01","date_published":"1994-01-01","updated_at":"2026-07-22T22:19:21Z","subjects":["thermoplastics"],"languages":["en"],"rights":["In Copyright"],"rights_urls":["http://rightsstatements.org/vocab/InC/1.0/"],"identifier_entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["etd-01252008-165523"],"render_values":[{"text":"etd-01252008-165523","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/10919/37216","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.committeechair","label":"Committee Chair","values":["Stinchcomb, Wayne W."]},{"key":"dc:contributor.committeemember","label":"Committee Member","values":["Kander, Ronald C.","Kriz, Ronald D.","Loos, Alfred C.","Reifsnider, Kenneth L."]},{"key":"dc:contributor.department","label":"Department","values":["Engineering Science and Mechanics"]},{"key":"dc:creator","label":"Author","values":["Subramanian, Suresh"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2014-03-14T21:08:54Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2014-03-14T21:08:54Z","2008-01-25"]},{"key":"dc:date.issued","label":"Date","values":["1994-01-01"]},{"key":"dc:publisher","label":"Institution","values":["Virginia Tech"]},{"key":"dc:type","label":"Dc Type","values":["Dissertation"]},{"key":"dc:type.dcmitype","label":"Dc Type Dcmitype","values":["Text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Engineering Science and Mechanics"]},{"key":"thesis:degree_level","label":"Degree Level","values":["doctoral"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Ph. 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Three material systems having the same Apollo graphite fibers and HC 9106-3 toughened epoxy matrix, but with different fiber surface treatments and sizings were used in this study. The fibers used in the 810A and 820 A systems received 100% and 200% industry standard surface treatments respectively and were sized with Bisphenol-A unreacted epoxy material. The 810 O system was manufactured with 100% surface treated fibers that were sized with pvp (polyvinylpyrrolidone), a thermoplastic material. The presence of different interphase in these materials was confirmed using a permanganic etching technique. Results indicate that the interphase is discontinuous and made of linear chain polymeric material in the 810 A system. The interphase in the 810 O system has a gradient morphology while the 820 A system does not possess a well defined interphase. Mechanical test results indicate that the 810 O system significantly greater longitudinal tensile strength and failure strain compared to the 810 A system. The 810 A and 820 A systems have similar longitudinal tensile properties. Transverse tensile test results indicate that the 820 A system has the highest strength while the 810 O system has the lowest strength. The (0,90₃), cross-ply laminates from the three material systems exhibit different damage mechanisms and failure modes under monotonic tensile loading. Fatigue test results indicate that the 810 O laminates have longer fatigue lives at higher load levels and shorter fatigue lives at lower load levels compared to the 810 A laminates. The 820 A laminates have longer life compared to the other two materials systems, at all three load levels. The 810 O material exhibits greater damage and stiffness reduction than the other two materials. The 810 A and 820 A systems exhibit a brittle stress concentration controlled failure, while the pvp sized 810 O system exhibits a global strain conuolled failure. A micromechanics model was developed to investigate the role of the interphase on the tensile strength of unidirectional laminates. A new parameter called the ‘efficiency of the interface’, is introduced in the model. A simple scheme that uses the experimentally determined tensile modulus of unidirectional laminates in a concentric cylinders model, is described to estimate the interfacial efficiency. The tensile fatigue performance of cross-ply laminates is predicted using this micromechanics model in a cumulative damage scheme. The predicted fatigue lives and failure modes agree well with experimental results."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["Ph. D."]},{"key":"dc:format.mimetype","label":"Dc Format Mimetype","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Effect of fiber/Matrix Interphase on the Long Term Behavior of Cross-Ply Laminates"]}]}],"canonical_facts":{"dc:contributor.committeechair":["Stinchcomb, Wayne W."],"dc:contributor.committeemember":["Kander, Ronald C.","Kriz, Ronald D.","Loos, Alfred C.","Reifsnider, Kenneth L."],"dc:contributor.department":["Engineering Science and Mechanics"],"dc:creator":["Subramanian, Suresh"],"dc:date.accessioned":["2014-03-14T21:08:54Z"],"dc:date.available":["2014-03-14T21:08:54Z","2008-01-25"],"dc:date.issued":["1994-01-01"],"dc:description.abstract":["A systematic study was conducted to examine the influence of fiber surface treatment and sizing on the formation of fiber-matrix interphase and its effects n the mechanical properties of composite laminates. Three material systems having the same Apollo graphite fibers and HC 9106-3 toughened epoxy matrix, but with different fiber surface treatments and sizings were used in this study. The fibers used in the 810A and 820 A systems received 100% and 200% industry standard surface treatments respectively and were sized with Bisphenol-A unreacted epoxy material. The 810 O system was manufactured with 100% surface treated fibers that were sized with pvp (polyvinylpyrrolidone), a thermoplastic material. The presence of different interphase in these materials was confirmed using a permanganic etching technique. Results indicate that the interphase is discontinuous and made of linear chain polymeric material in the 810 A system. The interphase in the 810 O system has a gradient morphology while the 820 A system does not possess a well defined interphase. Mechanical test results indicate that the 810 O system significantly greater longitudinal tensile strength and failure strain compared to the 810 A system. The 810 A and 820 A systems have similar longitudinal tensile properties. Transverse tensile test results indicate that the 820 A system has the highest strength while the 810 O system has the lowest strength. The (0,90₃), cross-ply laminates from the three material systems exhibit different damage mechanisms and failure modes under monotonic tensile loading. Fatigue test results indicate that the 810 O laminates have longer fatigue lives at higher load levels and shorter fatigue lives at lower load levels compared to the 810 A laminates. The 820 A laminates have longer life compared to the other two materials systems, at all three load levels. The 810 O material exhibits greater damage and stiffness reduction than the other two materials. The 810 A and 820 A systems exhibit a brittle stress concentration controlled failure, while the pvp sized 810 O system exhibits a global strain conuolled failure. A micromechanics model was developed to investigate the role of the interphase on the tensile strength of unidirectional laminates. A new parameter called the ‘efficiency of the interface’, is introduced in the model. A simple scheme that uses the experimentally determined tensile modulus of unidirectional laminates in a concentric cylinders model, is described to estimate the interfacial efficiency. The tensile fatigue performance of cross-ply laminates is predicted using this micromechanics model in a cumulative damage scheme. The predicted fatigue lives and failure modes agree well with experimental results."],"dc:description.degree":["Ph. D."],"dc:format.mimetype":["application/pdf"],"dc:identifier.other":["etd-01252008-165523"],"dc:identifier.uri":["http://hdl.handle.net/10919/37216"],"dc:language.iso":["en"],"dc:publisher":["Virginia Tech"],"dc:rights":["In Copyright"],"dc:rights.uri":["http://rightsstatements.org/vocab/InC/1.0/"],"dc:subject":["thermoplastics"],"dc:title":["Effect of fiber/Matrix Interphase on the Long Term Behavior of Cross-Ply Laminates"],"dc:type":["Dissertation"],"dc:type.dcmitype":["Text"],"thesis:degree_discipline":["Engineering Science and Mechanics"],"thesis:degree_level":["doctoral"],"thesis:degree_name":["Ph. D."],"thesis:institution_name":["Virginia Polytechnic Institute and State University"]},"updated_at":"2026-07-22T22:19:21Z"}